Infections are one of the major reasons why nursing home residents are hospitalized and a significant source of morbidity of this population group. Although Infection Control programs are computerized at the hospital level, no integrated computer assisted Infection Control programs exist for nursing homes. We have developed a computer program, The Patient Care System (PCS) which integrates a variety of functions in a nursing home setting and which has a strong clinical orientation. Unlike other commercial programs, our program is written in the command language of a relational data base manager. This feature allows the presentation of standard screens of a "vertical", task oriented specific program, while maintaining the data bases open for idiosyncratic query or the writing of local independent programs. The program can be used for management, quality assurance, and research purposes. We propose to develop a computer assisted Infection Control program which will be integrated into PCS as a module to avoid redundancy of data input. Utilizing this program, we propose to study (1) the relationship of infection to impairment level of a nursing home population and (2) the appropriateness of antibiotic use at a nursing home.